Department of Electrical Engineering and Information Systems, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
Adv Mater. 2019 Oct;31(43):e1903687. doi: 10.1002/adma.201903687. Epub 2019 Sep 9.
Highly responsive organic image sensors are crucial for medical imaging applications. To enhance the pixelwise photoresponse in an organic image sensor, the integration of an organic photodetector with amplifiers, or the use of a highly responsive organic photodetector without an additional amplifying component, is required. The use of vertically stacked, two-terminal organic photodetectors with photomultiplication is a promising approach for highly responsive organic image sensors owing to their simple two-terminal structure and intrinsically large responsivity. However, there are no demonstrations of an imaging sensor array using organic photomultiplication photodetectors. The main obstacle to a sensor array is the weak-light sensitivity, which is limited by a relatively large dark current. Herein, a highly responsive organic image sensor based on monolithic, vertically stacked two-terminal pixels is presented. This is achieved using pixels of a vertically stacked diode-type organic photodetector with photomultiplication. Furthermore, applying an optimized injection electrode and additionally stacked rectifying layers, this two-terminal device simultaneously demonstrates a high responsivity (>40 A W ), low dark current, and high rectification under illumination. An organic image sensor based on this device with an extremely simple architecture exhibits a high pixel photoresponse, demonstrating a weak-light imaging capability even at 1 µW cm .
高响应有机图像传感器对于医学成像应用至关重要。为了增强有机图像传感器中的像素级光响应，可以将有机光电探测器与放大器集成，或者使用无需额外放大组件的高响应有机光电探测器。使用具有倍增功能的垂直堆叠的两终端有机光电探测器是实现高响应有机图像传感器的一种很有前途的方法，因为它们具有简单的两终端结构和固有的大响应度。然而，目前还没有使用有机倍增光电探测器的成像传感器阵列的演示。传感器阵列的主要障碍是弱光灵敏度，这受到相对较大暗电流的限制。在此，提出了一种基于单片垂直堆叠两终端像素的高响应有机图像传感器。这是通过使用具有倍增功能的垂直堆叠二极管型有机光电探测器的像素来实现的。此外，通过应用优化的注入电极和另外堆叠的整流层，这种两终端器件在光照下同时表现出高响应度（>40 A W ）、低暗电流和高整流。基于这种具有极简单结构的器件的有机图像传感器表现出高像素光响应，即使在 1 µW cm 的弱光下也具有成像能力。
